Following a two week merge window following the release of the Linux 2.6.33 kernel, Linus Torvalds has announced the first release candidate for the next kernel, to be known as the Linux 2.6.34 kernel.Of a lot of interest to us (and likely you too) are all of the GPU DRM updates in the Linux 2.6.34 kernel that includes GPU hybrid switching, initial ATI Radeon HD 5000 series KMS support (a.k.a. "Evergreen"), controversial Nouveau changes, ATI Radeon KMS power management support, Intel Sandy Bridge support, and much more.Outside of the graphics fun in this kernel to be officially released next quarter is a new filesystem (Logfs), a hardware driver for Apple's Magic Mouse, virtualization improvements, and other updates particularly to the Linux drivers and architectures.The Linux 2.6.34-rc1 kernel release announcement can be read at LKML.org...

The options you wrote about in the previous post are picked up by the Xorg DDX driver, making it manage some aspects of the GPU power management, in userspace.

The New(r) Improved(tm) All-Round Better(?) way is DRM power management. This permits a centralized management of the GPU and video memory current, voltages, and what else lies inbetween, whereas the temporary userspace solution would have had to synchronize its Power Management decisions with the other DRM/GPU clients, if it ever did it at all. This Better(stop it!) solution has the advantage to provide Power Management during the whole Linux(tm, not a joke)-Experience(this is), and permits a closer control of the video GPU/memory status.

So, it is way better. :)

What you need? Enable KMS, as that's a completely new DRM module, in which the developers are implementing all the good things you're reading here on Phoronix.

Next? Edit your Linux kernel command line to include this options:

radeon.modeset=1 radeon.dynpm=1

Then, pray whathever ancient god of luck and good and fortune you could know of. Then, and only then, boot into your operating system.

And say thank you to the devs.
They actually are those gods I was talking about.

03-10-2010, 08:08 PM

Melcar

With my HD4850, I can see the 4 powerstates being listed. Each one has (or should) 3 modes. This I learned before from messing around with Radeon Bios Editor. In the kernel log, state 0 and 3 each have three modes, and modes 1 and 2 show only two. Looking at the listed frequencies, it seems that the actual "3D" frequencies are missing. I see the low "2D" clocks in there, but not the high power ones. Is this a current limitation, or a problem with my particular setup?
Also, this rc causes a weird kernel panic on my laptop (Presario V2000) and I'm unable to go past the grub2 menu.

03-10-2010, 08:45 PM

Melcar

As far as PM, it does seem to work. The core is downclocking fine as far as I can tell, which is making things slower than usual; KMS makes 2D slow as is, so the downclocking is making things worse :p.